This blog began through a NIFA grant for Missouri Beginning Farmers. It continues today as a way for beginning farmers to learn about new ideas and to hear about upcoming events of interest. It is maintained by Debi Kelly (kellyd@missouri.edu).

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As an Extension Associate with the University of Missouri, I work with beginning farmers, small farms, alternative agriculture and organic farming. I am also the Co-coordinator for the Missouri Sustainable Agriculture and Research (SARE) Education Professional Development Program (PDP).

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Tuesday, April 7, 2015

Grafting Research Could Rescue Watermelon Crop

The watermelon crop has declined dramatically
in Washington because of disease. But Washington State University researchers
are developing a solution that involves grafting watermelon plants onto squash
and other vine plant root stocks.

“We’ve lost about a third of our state’s
watermelon production over the last 10 years because of Verticillium wilt,”
said Carol Miles, a professor of vegetable horticulture at the WSU Northwestern
Washington Research and Extension Center in Mount Vernon. “Growers have
switched to other crops that are less susceptible.”

Today, there are about 550 acres of
watermelon grown in Washington, with a value of approximately $5 million.

Miles said growers can lose 25-75 percent of
their yield to the disease – but this loss does not occur until the very end of
the growing season. That’s when the damage from Verticillium appears.

The fungus also affects tomatoes, potatoes,
eggplant and many other crops and plants.

Watermelon grafting used
worldwide

Last fall, Miles received a $138,000 grant
from the state agriculture department to look into grafting, a solution that
doesn’t require fumigants. She is also working with a national team of
researchers on a $3 million U.S. Department of Agriculture grant. Her portion
is $171,000 to look at grafting tomato and eggplant.

Grafting involves cutting a young seedling
from its roots and attaching it to the roots of a related plant that is disease
resistant. The grafted plant produces fruits that are equivalent or better in
quality than those of non-grafted plants.

“Grafting is very old technology, going back
over 1,500 years in China,” Miles said. “Farmers in Japan have used grafted
watermelon since the 1920's. In the Mediterranean region, farmers have been
using grafted watermelon, tomato and eggplant for almost 20 years.

“We just need to find out what works best for
our region and we’ll solve the Verticillium wilt problem,” she said.

Testing root stocks in the field

Her research involves testing which plants
work best together under Washington growing conditions and which root stocks are
most resistant to Verticillium wilt.

The first goal is to increase the survival
rate for newly grafted watermelon plants. If only 25 percent survive, the effort
is not worth it, Miles said.

The second goal is to find successful plant
combinations that are disease resistant and have equivalent fruit yield and
quality, compared to non-grafted plants grown in healthy soil. Miles and her
team are testing watermelon grafted to pumpkin, squash and bottle gourd because
they are all resistant to Verticillium wilt.

This year will be the second of a two-year
field study. While these studies actually started about five years ago under a
previous grant, Miles and her team are applying new information that they have
learned along the way. They will have two full years of testing in commercial
fields by the end of the grants.